1. Field of the Invention
The present invention relates to a method for automatically calibrating an electronic sphygmomanometer, more particularly to a method for automatically calibrating an electronic sphygmomanometer by installing an additional set of pressure sensors to the electronic sphygmomanometer, so that users can compare the values of a set of pressure sensors used at regular time and the values of at least one set of pressure sensors through specified air pressure values and settings to determine whether or not the pressure sensors used at regular time are normal; if not, then shut down such pressure sensors, so that users can continue measuring blood pressure for the next time with the normal set of pressure sensors.
2. Description of the Related Art
In general, the pressure sensors (not shown in the figure) of a traditional electronic sphygmomanometer will lose their precision after being used for a period of time, which results in an inaccurate measurement. General users are unable to calibrate the traditional electronic sphygmomanometer on their own, but users have to send the electronic sphygmomanometer back to the original manufacturer for the calibration or the electronic sphygmomanometer is calibrated by an experienced medical professional or a doctor with related equipments. Please refer to FIG. 1 for a prior-art calibration method, which prepares a mercury sphygmomanometer 100 first, and the mercury sphygmomanometer is used as a standard calibrating instrument. With a T-shape interconnected pipe 110, the testing electronic sphygmomanometer 300 is interconnected with the mercury sphygmomanometer 100, while the interconnected pipe 110 is coupled to a manual water pump. Therefore, an air cuff 200 of the calibrating electronic sphygmomanometer 300 is wrapped around the cylinder 400 of a simulated arm of the electronic sphygmomanometer 300. When a power switch (not shown in the figure) situated on the testing electronic sphygmomanometer 300 is pressed, the testing electronic sphygmomanometer 300 is started to switch the operating mode of the testing electronic sphygmomanometer 300 to a testing mode. The air cuff 200 of the testing electronic sphygmomanometer 300 is inflated by the manual air pump 500 and thus the cylinder 400 is pressurized. After the cylinder 400 is pressurized to a specific level, the readings measured by the mercury sphygmomanometer 100 and the testing electronic sphygmomanometer 300 are compared. If the readings match with each other, it is not necessary to calibrate the testing electronic sphygmomanometer 300; if the readings mismatch with each other, it is necessary to adjust the reading of the testing electronic sphygmomanometer 300 to the same value of the reading of the mercury sphygmomanometer 100. The aforementioned procedure is repeated until the reading of the testing electronic sphygmomanometer 300 is equal to the reading of the mercury sphygmomanometer 300. If the adjustment to the same value cannot be made, then it is necessary to replace the pressure sensor or send the electronic sphygmomanometer back to the original manufacturer for calibration. Such arrangement not only wastes time, but also requires professional users to calibrate the electronic sphygmomanometer, which is inconvenient in its use.